1. Technical Field
The present disclosure relates to apparatus and methods for inspecting and analyzing semiconductor wafers and other substrates using scatterometry and related techniques.
2. Description of the Background Art
Scatterometry refers to an optical technique that analyzes diffraction to deduce structural details of a diffracting sample. The diffracting sample is generally a periodic structure, that is, a grating. Scatterometry may be used to measure or analyze two-dimensional structures (line gratings), as well as three-dimensional structures (such as periodic patterns of mesas or vias on a substrate).
Metrology methods using scatterometry rely on being able to accurately model the features that are being measured, calculate the light diffraction properties of the feature, and find a match between the calculated and measured values. In other words, theoretical model is defined for each physical structure to be analyzed, and calculated data using the model is then compared or analyzed against measured data. Typically, the measured data are related to the light diffraction efficiency as a function of wavelength, incidence angle, or both.
It is desirable to improve inspection and metrology for the manufacture of semiconductors and other substrates.